Field of the Invention
The present invention generally relates to a barrier for use with a downhole tool. More particularly, the invention relates to an expandable mesh barrier for use with a downhole pump.
Description of the Related Art
When an oil well is first drilled and completed, the fluids (such as crude oil) may be under natural pressure that is sufficient to produce on its own. Over time, the natural pressure may decline to the point where the oil must be artificially lifted to the surface. A rod pump may be used to artificially lift the oil to the surface. A string of sucker rods extends down to a pump located downhole and is reciprocated to operate the pump.
One issue encountered during use of the rod pump is that particulates (sand, iron oxides, etc) entrained in a producing fluid may settle down in the annular area between the barrel of the pump and the tubing. As the particulates build up to several feet in height, they will “pack” into this annular area and cause the pump barrel to become stuck in the tubing.
There are devices available in the industry designed to address this issue. For example, a “top seal” can be installed onto the top of the pump barrel to prevent particulates from falling into the annular region between the barrel and the tubing. One such prior art design of a top seal incorporates a rubber “finned” element that consists a number of radially protruding rubber disks or fins. With this type of design, the fins may become brittle due to excessive heat or the fins may become weak due to excessive flexural fatigue when travelling down the wellbore. This may result in the fins parting from the top seal assembly and falling down into the wellbore.
There is a need, therefore, for an improved mechanism that could effectively prevent particulates from accumulating between the barrel and the tubing.